Biometric systems are emerging technologies that enable the authentication of an individual based on physiological or behavioral characteristics. Biometric techniques include recognizing faces, fingerprints, hand geometry, palms, voices, gait, irises, signature, etc. Among these biometric identifiers, fingerprint recognition is considered the most popular and efficient technique. However, a fingerprint sensor system is subject to various threats such as attacks at the sensor level, replay attacks on the data communication stream, and attacks on the database. A variety of fingerprint sensors may be spoofed through fake fingers using moldable plastic, clay, Play-Doh, wax or gelatin. From a security and accountability perspective, a biometric system should have the ability to detect when fake biometric samples are presented.